Butterflies are present in Hawaiʻi, but the fauna is highly unusual due to the archipelago’s extreme geographic isolation. The native population is remarkably small, consisting of only two species that evolved on the islands and are found nowhere else. This small number of true natives is overshadowed by a much larger group of common, recently arrived species. Most butterflies encountered today are introduced species that successfully colonized the islands after the arrival of humans.
The Unique Native Hawaiian Butterflies
Hawaiʻi is home to only two endemic butterfly species. This low number reflects the difficulty butterflies had in reaching and establishing themselves in the Pacific Ocean. Survival required finding a suitable host plant for their caterpillars upon arrival.
The most recognized species is the Kamehameha butterfly, the state insect, known as the Pulelehua (Vanessa tameamea). Its caterpillars feed exclusively on native nettles, such as māmaki (Pipturus albidus). The species is now restricted mostly to wet forest habitats at higher elevations where host plants are abundant and invasive pressures are reduced.
The second endemic species is the Hawaiian blue or Blackburn’s blue (Udara blackburni), a much smaller butterfly with iridescent azure wings. Its caterpillars feed on native plants like koa (Acacia koa) and ʻaaliʻi (Dodonaea viscosa).
These native species are difficult to observe, often requiring hikes into protected native forest areas. Their rarity contrasts sharply with the abundance of non-native butterflies seen in urban environments. The Hawaiian blue is slightly more widespread than the Kamehameha butterfly because its host plants occur across a broader range of habitats.
Common Introduced and Migratory Species
The vast majority of butterflies seen across the islands are non-native species that established permanent populations in the last two centuries. At least 16 non-native species have become established, thriving in human-altered landscapes. These common species are the ones the average person is most likely to encounter in parks and backyards.
The Monarch butterfly (Danaus plexippus) is one of the most recognizable introduced species and is widespread. Its presence is linked to the introduction of its host plant, tropical milkweed (Asclepias curassavica), brought to Hawaiʻi in the mid-1800s. Unlike mainland counterparts, the Hawaiian Monarch population is non-migratory, breeding year-round due to the stable tropical climate.
Another common sight is the Cabbage White (Pieris rapae), first recorded on Oʻahu around 1897. This species is native to Europe and Asia but spread globally, often as a stowaway in cargo. Its larvae, known as “imported cabbageworms,” feed on plants in the mustard family, including cultivated crops like cabbage and broccoli.
The Gulf Fritillary (Agraulis vanillae) is a bright orange butterfly that colonized the islands following the introduction of its host plant, various passion vine species (Passiflora spp.). This species was recorded on six main islands by the early 2000s.
Conservation Status and Ecological Threats
The two endemic Hawaiian butterfly species face significant pressures that threaten their survival, primarily stemming from introduced species and habitat loss. A major threat is predation by non-native invertebrates, especially ants and parasitic wasps, which attack the eggs and caterpillars. More than 60 species of non-native ants have established themselves in Hawaiʻi, acting as effective predators in lowland areas.
Habitat destruction and alteration also pose a challenge due to invasive plants and human development. Both the Kamehameha butterfly and the Hawaiian blue are being pushed to higher elevations because invasive flora replaces their native host plants in lower elevation forests. This loss of habitat confines native populations to smaller, fragmented areas.
Competition for resources also occurs, as introduced butterflies compete with native species for nectar. Conservation efforts focus on restoring native forests by controlling invasive plants and predators. Active management programs, such as captive rearing, attempt to boost the populations of the Kamehameha butterfly and reintroduce them into restored habitats.